1. Field
The present disclosure relates generally to the use of an interoral appliance, such as a palate retainer configured with a nasopharyngeal extension. The nasopharyngeal extension is a tube or airway extender that fits behind the soft palate with the lumen large enough to allow adequate air to pass behind the soft palate in the nasopharynx. It may also be extended to pass upwards behind the soft palate and downwards behind the base of tongue.
2. Discussion of the Background Art
The sleep apnea syndrome, and in particular obstructive sleep apnea, afflicts an estimated 2-5% of the general population and is due to episodic upper airway obstruction during sleep. Those afflicted with obstructive sleep apnea experience sleep fragmentation and intermittent, complete or nearly complete cessation of ventilation during sleep with potentially severe degrees of oxyhemoglobin unsaturation. These features may be translated clinically into debilitating daytime sleepiness, cardiac disrhythmias, pulmonary-artery hypertension, congestive heart failure and cognitive dysfunction. Other problems related to sleep apnea include carbon dioxide retention during wakefulness as well as during sleep, and continuous reduced arterial oxygen tension. Hypersomnolent sleep apnea patients may be at risk for excessive mortality from these factors as well as from an elevated risk for accidents such as while driving or operating other potentially dangerous equipment.
Although details of the pathogenesis of upper airway obstruction in sleep apnea patients have not been fully defined, it is generally accepted that the mechanism includes either anatomic or functional abnormalities of the upper airway which result in increased air flow resistance. Such abnormalities may include narrowing of the upper airway due to suction forces evolved during inspiration, the effect of gravity pulling the tongue back to appose the pharyngeal wall, and/or insufficient muscle tone in the upper airway dilator muscles. It has also been hypothesized that a mechanism responsible for the known association between obesity and sleep apnea is excessive soft tissue in the anterior and lateral neck which applies sufficient pressure on internal structures to narrow the airway.
One theory of the cause for the sleep disturbance is the relaxation of the tongue and pharyngeal walls to varying degrees during the several stages of sleep. When fully awake, these tissues have normal tone as air passes in and out of the lungs during respiration. However, during sleep, the musculature supporting these tissues relaxes. As air is inspired, the tongue and posterior walls of the pharynx collapse, causing snoring or more seriously causing partial or complete obstruction of the airway.
Obstructive sleep apnea occurs due to a collapse of soft tissue within the upper airway during sleep. The ongoing force of inspiration serves to generate increasingly negative pressure within the pharynx, causing further collapse. The lack of respiration results in inadequate blood oxygenation, and rising carbon dioxide levels. The cardiovascular response produces an increase in the blood pressure and pulse, and cardiac arrhythmias often occur. The carbon dioxide increase and oxygen desaturation triggers a transition to a lighter sleep stage, usually without wakefulness. This transition brings a return to tonicity of the muscles of the upper airway, allowing normal breathing to resume. The person then returns to deeper stages of sleep and the process is repeated. The disease is quantified in terms of respiratory disturbances per hour. Mild disease begins at 2-3 APNEAS per hour, and it is not uncommon to find patients with indices of about one hundred or more.
Not surprisingly, sleep is extremely fragmented and of poor quality in persons suffering from sleep apnea. As a result, such persons typically feel tired upon wakening and may fall asleep at inappropriate times during the day. All aspects of quality of life, from physical and emotional health, to social functioning are impaired by obstructive sleep apnea.
Surgical Treatments
The treatment of sleep apnea has included such surgical interventions as Uvulopalatopharyngoplasty (UPPP) gastric surgery for obesity, and maxillo-facial reconstruction. Another mode of surgical intervention used in the treatment of sleep apnea is tracheostomy. These treatments constitute major undertakings with considerable risk of post-operative mortality. In UPPP, any remaining tonsil tissue and a portion of soft palate is removed. The procedure often increases the nasopharyngeal airway. However, UPPP does not always fix a sagging soft palate nor does it address apnea caused by obstructions caused by the base of the tongue being deeper in the oropharynx part of the airway. These surgical techniques are extremely invasive, requiring general anesthesia, and a prolonged, painful recovery.
LAUP, or Laser-Assisted Uvulopalatoplasty, is a modification of the above-mentioned technique, but has had mixed success and cannot solve obstructions in the foropharynx part of the airway or sleep apnea.
Radio frequency tissue ablation (RFTA) with the trade name “Somnoplasty,” has been used to shrink the soft palate, uvula and reduce tongue volume in the treatment of snoring and obstructive sleep apnea. Somnoplasty utilizes a radiofrequency tool that generates heat to create coagulative lesions at specific locations within the upper airway. The lesions created by the procedure are naturally resorbed in approximately three to eight weeks, reducing excess tissue volume and increasing the airway opening. Like UPPP and LAUP, more than one session is typically required, and other surgeries may still be necessary in moderate to severe cases, and there are occasional problems with morbidity.
Another area of surgical interest lies in techniques designed to pull the tongue anteriorly. The most recent such surgical system designed to treat snoring (as well as obstructive sleep apnea) was approved by the FDA in February 1998. Known as the tongue suspension procedure (with the trade name Repose), it is intended to pull the tongue forward, thereby keeping the tongue from falling into the airway during sleep. The system utilizes a bone screw inserted into the mandible. The screw attaches to a non-absorbable suture which travels the length of the tongue and back. Similarly, the hyoid bone can be drawn anteriorly with two distinct screws, also attached to the mandible.
Techniques have also been developed for treating, specifically, the condition of snoring. Conrad et al., U.S. Pat. No. 6,250,307 discloses a method for treating snoring of a patient, which includes embedding an implant into a soft palate of a patient in order to alter a dynamic response of a soft palate to airflow. The methods of Conrad et al. are specifically designed to reduce the audibility of snoring but do not address the more serious condition of sleep apnea.
These conventional treatments continue to suffer poor cure rates. The failures lie in their inability to maintain patency in the retropalatal region and retroglossal region (the caudal margin of the soft palate to the base of the epiglottis). The poor success rates combined with high morbidity from some of the surgical interventions, contribute to an ongoing need for more effective treatments for sleep apnea and/or snoring.
Pharmacological Treatments
Pharmacological therapy, aimed at stimulating upper airway muscle to reduce apneas, also have, in general, been disappointing. In addition, side effects from the pharmacological agents that have been used are frequent. Thus, medical practitioners continue to seek non-invasive modes of treatment for sleep apnea with high success rates and high patient compliance including, for example in cases of minor to moderate sleep apnea relating to obesity, weight loss through a regimen of exercise and regulated diet.
Other Non-Surgical Treatments
Other non-surgical treatments for sleep apnea include the use of oral devices and appliances that work to prevent the tongue from falling backwards or help reduce the collapse of the soft palate. Still other treatments involve the use of retainers that push the lower jaw forward, thereby pulling the tongue slightly forward and, in some cases, helping elevate the soft palate. Also, there are devices that pull on the tongue to keep it forward during sleep. These current oral devices typically do not create a significant improvement except in mild to moderate cases and can be associated with movement of the teeth over time of problems with the temporamandibular joint.
Recent work in the treatment of sleep apnea has included the use of continuous positive airway pressure (CPAP) to maintain the airway of the patient in a continuously open state during sleep. For example, U.S. Pat. No. 4,655,213 and Australian patent AU-B-83901/82 both disclose sleep apnea treatments based on continuous positive airway pressure applied within the airway of the patient.
Also of interest is U.S. Pat. No. 4,773,411 which discloses a method and apparatus for ventilatory treatment characterized as airway pressure release ventilation and which provides a substantially constant elevated airway pressure with periodic short term reductions of the elevated airway pressure to a pressure magnitude no less than ambient atmospheric pressure.
Although CPAP has been found to be very effective and well accepted, it suffers from some of the same limitations, although to a lesser degree, as do the surgical options; specifically, a significant proportion of sleep apnea patients do not tolerate CPAP well. Thus, development of other viable non-invasive therapies has been a continuing objective in the art.
Still others have attempted to solve sleep apnea disorders using intraorally fitted appliances, including U.S. Pat. Nos. 4,981,437 and 4,932,867, that disclose a method and apparatus for constructing dentures, which are useful, for example, in treating breathing disorders. U.S. Pat. No. 4,386,405 discloses a device for measuring the location, attitude, or change of location of a patient's lower jaw. U.S. Pat. No. 4,859,181 relates to optical measurement of jaw movement. U.S. Pat. Nos. 3,998,209 and 4,220,142 disclose conditioning systems for use in a program of behavior modification to eliminate snoring, while U.S. Pat. No. 4,976,618 relates to treatment of temporomandibular joint dysfunction and bruxism. U.S. Pat. No. 3,297,021 discloses an intraoral strain gauge and telemetering of information from an intraoral location to an outside indicator.
The following U.S. patents purport to relate to tongue positioning and/or retaining apparatus: U.S. Pat. Nos. 5,154,184, 5,092,346, 5,046,512, 4,676,240, 4,169,473, 4,304,227 and 4,593,686. Other patents addressing the matter of tongue positioning include the following: U.S. Pat. Nos. 5,649,540, 5,465,734, 5,373,859, 5,052,409, 4,715,368, 4,196,724, 3,884,226, 3,312,216 and 3,132,647, as well as European Patent 0182387 and British Patent 874,480. The following patents purport to relate to chin straps or similar apparatus intended to hold the jaw closed: U.S. Pat. Nos. 3,312,217, 2,711,730 and 1,990,411.
Other patents relate to apparatus for interaction with the soft palate in the user's oral cavity. These include U.S. Pat. Nos. 4,669,459 and 5,316,020, German patent no. DE 40 26 602 and European patent no. EP 0264516. Other patents of general interest include U.S. Pat. Nos. 5,056,534 and 2,705,006, German patent nos. 65194 and 2320501, and PCT publication no. WO 92/05752 and European patent application no. 0 487 469 A1.
While the above-identified conventional devices and surgical techniques are purported to treat upper airway instability, such as OSA or snoring, they are successful, if at all, in only a limited pool of patients or under limited circumstances. Therefore, there remains a relatively large number of patients whose airway disorder is believed to be treatable using an intraoral appliance, yet conventional appliances are ineffective, overly burdensome, uncomfortable, or any combination thereof.
The present disclosure overcomes the aforementioned disadvantages of the prior art by using a novel palate retainer with a nasopharyngeal extension, wherein the nasopharyngeal extension fits behind the soft palate with a tube that has a lumen large enough to allow for the passage of air in the nasopharynx.
The present disclosure also provides many additional advantages, which shall become apparent as described below.